1. Field of the Invention
The present invention relates to a satellite radio receiving antenna and a satellite radio wave receiving system for receiving satellite radio broadcasting, and more particularly, to a satellite radio receiving antenna suitably provided on the inner surface of a windowpane (in the interior) in a vehicle and a satellite radio receiving system using the satellite radio receiving antenna.
2. Description of the Related Art
In recent years, a satellite broadcasting system in which signals including audio and video information are transmitted from a broadcasting satellite for broadcasting has been in wide use. At present, in the United States of America, audio sound information provided by such a satellite broadcasting system, so-called satellite radio broadcasting is provided by XM Satellite Radio Inc. In the satellite radio broadcasting system, signals transmitted from a satellite can be received in a wide area on the earth, and therefore the broadcasting can be received and listened to not only in fixed locations such as in general households with a receiver, but also in a moving body (vehicle) such as an automobile with a receiver provided in the moving body. The latter case has attracted much attention (see Japanese Patent Laid-Open No. 2003-198235).
In a satellite radio receiving system, when a receiver is provided in a vehicle, the location of the receiving antenna is crucial. In the conventional satellite radio receiving system, the antenna is typically provided on the roof of the vehicle. However, when the antenna is provided on the exterior of the vehicle in this way, the receiving antenna must have water and weather resistance, which complicates the structure of the receiving antenna and pushes up the cost. When the antenna is provided on the exterior of the vehicle, a signal line must be extended from the receiving antenna to a receiver provided in the vehicle, and it is therefore troublesome and much costly to provide the satellite radio receiving system.
When such a receiving antenna is provided inside an automobile in order to solve the above described problem, the roof and pillars of the automobile that are typically made of a metal that obstructs signals to be received from a satellite, which narrows the field of view for receiving by the antenna and degrades the receiving characteristic. The satellite radio receiving antenna must have wide directivity, but when the antenna is provided in a vehicle, the roof does not serve as a ground plate, and therefore sufficient directivity is not provided.